Directional Ultra-wideband Antenna Research Articles

Dual-Polarized Directive Ultrawideband Antenna Integrated With Horn and Vivaldi Array

A novel ultrawideband dual-polarized H-plane horn antenna incorporated with a Vivaldi array is proposed. Aiming at ultrawide low-frequency applications that require dual-polarization with a compact shape, the proposed antenna employs an all-metal shared aperture structure. Different from the conventional dual-polarized horn where dual polarization is achieved using two orthogonal modes of the same waveguide, the proposed antenna uses two different types of transmission line for feeding: rectangular waveguide for vertically polarized (VP) H-plane horn antenna, and slot line for horizontally polarized (HP) Vivaldi antenna array. The Vivaldi slot significantly increases the HP bandwidth compared to the typical dual-polarized horn antennas, and does not disturb the VP radiation pattern. The proposed antenna has a measured -10 dB impedance bandwidth of 103% for HP mode, and 77.5% for VP mode. The measured peak gain for HP is 13.0 dBi and 14.3 dBi for VP. The simulated and measured results are in good alignment.

Design of miniaturized directional ultra wide band antenna for cancer detection

Design of miniaturized directional ultra wide band antenna for cancer detection

Design of high gain/directional ultra-wideband antenna for radar imaging systems

A compact size of 40 × 40 mm2 ( λ0 × λ0) semi-elliptical slotted ground structure (SESGS) directional ultra-wideband (UWB) antenna is proposed for radar imaging applications. A vertical semi-elliptical slot is inserted into ground and subsequently, an axis of semi-ellipse is rotated diagonally (with 45°) in direction of the substrate. Axes of semi-ellipse are optimized symmetrically around the circular patch to work antenna as a reflector. Furthermore, semi-elliptical slot is rotated horizontally (with 90°) again to improve the impedance bandwidth. Proposed antenna achieves fractional bandwidth around 83% covering the UWB frequency range from 4.40 to 10.60 GHz (S11 < −10 dB) having 4.5/6/7/8/9.3/10.2 GHz resonant frequencies. Also, antenna is capable to send low-distortion Gaussian pulses with fidelity factor more than 95% in time-domain. Measured gain and half power beam width (HPBW) are 6.1-9.1 dBi and 44°-29° in 4.40-10.60 GHz band, respectively, which show an improvement of 1-3 dBi in gain and half power beam-width is reduced by 5°-10° when compared with previously designed antennas. Experimental results show good agreement with CST simulation.

DESIGN ANALYSIS AND MODELING OF DIRECTIONAL UWB ANTENNA WITH ELLIPTICAL SLOTTED GROUND STRUCTURE FOR APPLICATIONS IN C- &amp; X-BANDS

A modified technique to design directional ultra-wideband (UWB) antenna with slotted ground structure approach on the ground plane has been presented for applications in Cand X-bands. Initially, elliptical slot is inserted into ground and thereafter, the axis of ellipse is rotated 45 degrees in direction of the substrate. Minor axis of the ellipse is optimized to locate it symmetrically around the circular patch in order to obtain the full Cand X-band operations and also to enhance directivity. Thereafter, for further improvement in the directivity as well as gain, an elliptical slot in circular patch has also been introduced. The impedance bandwidth approximates about 95% covering the frequency ranging from 4.18–11.50 GHz. The return losses (S11) are −38 dB and −43 dB through simulation, which are −24 dB and −32 dB by measurement at 6.3GHz, 9.3GHz resonant frequencies, respectively. Simulated gain and half power beam width (HPBW) are 2.5–8.4 dB and 49–22 degrees in 4.18–11.50 GHz band, respectively. Gain and half power beam width (HPBW) of the proposed antenna improves by 1–2 dB and 5–10 degrees, respectively compared with previously designed antennas. Simulation of the antenna has been carried out on Computer Simulation Technology (CST) software on an FR-4 substrate having dielectric constant 4.3 of thickness 1.6mm. The measured results show good agreement with equivalent circuit model and CST simulation.

Cross-Configured Directional UWB Antennas for Multidirectional Pattern Diversity Characteristics

A cross configuration of directional ultrawideband (UWB) antennas for multidirectional pattern diversity characteristics is presented. Initially, a printed UWB circular monopole having an asymmetric curve shaped CPW feed is designed as a base antenna for obtaining a directional radiation pattern, direction of which remains fairly same for the entire UWB. This base antenna is attached to similar antennas, in a four element cross-configuration to achieve multidirectional pattern diversity characteristics. The proposed structure provides high inter-element isolation of more than 20 dB, with an impedance bandwidth of 19.7 GHz, i.e., 1.3 GHz to 20 GHz. Transmission and diversity characteristics of the proposed antenna are analyzed. Good agreement between simulated and measured results indicates that the proposed antenna is suitable for UWB pattern diversity applications.

Research on Ultra-Wideband TEM Horn Antenna and its Miniaturization

TEM horn antenna is one kind of directional Ultra-wideband antenna with simple structure. Based on the design method of TEM horn antenna, satisfied impedance and radiation character are obtained by simulation and experiment research. On this basis, by means of metal ridged loaded, background dielectric material loaded and distributed lossy metal loaded respectively, the miniaturization character is realized. The simulation analysis results show that load of traditional TEM horn antenna can get efficiently improvement in structure and performance which have widely application foreground in pulse radiation communication system and ultra-wideband radar system.

Directive Stacked Patch Antenna for UWB Applications

Directional ultrawideband (UWB) antennas are popular in wireless signal-tracking and body-area networks. This paper presents a stacked microstrip antenna with an ultrawide impedance bandwidth of 114%, implemented by introducing defects on the radiating patches and the ground plane. The compact (20×34 mm) antenna exhibits a directive radiation patterns for all frequencies of the 3–10.6 GHz band. The optimized reflection response and the radiation pattern are experimentally verified. The designed UWB antenna is used to maximize the received power of a software-defined radio (SDR) platform. For an ultrawideband impulse radio system, this class of antennas is essential to improve the performance of the communication channels.

Compact Directive Ultra-Wideband Rectangular Waveguide Based Antenna for Radar and Communication Applications

A new directive ultra-wideband antenna based on rectangular waveguide aperture antennas is presented. Conventional rectangular aperture antennas are limited by the single mode operation of the waveguide as well as relatively long and narrowband resonant feeds. To overcome these limitations, we developed a new rectangular waveguide antenna feeding structure that can establish an aperture field distribution very similar to that of the fundamental waveguide mode with a relatively short waveguide section and over two octaves of bandwidth. The overall antenna size is 0.55 λm × 0.27λm × 0.18 λm where λm is wavelength at the minimum operating frequency. Due to the planar aperture of the antenna, a polarizer could be added to the antenna to ensure good cross-polarization performance with fabrication tolerances. The proposed feed requires a balun structure, and thus an integrated balun design is presented. It is found that a standard balun would interact with the antenna structure and thus a modified design was implemented. The antenna was fabricated and measured. The antenna had VSWR <; 2.5 from 1.08 to 4.9 GHz and the measured gain showed almost constant aperture gain which increases from 5.3 dBi at the low frequency end to 11 dBi at the high frequency edge.

A Novel Low-Profile Compact Directional Ultra-Wideband Antenna: The Self-Grounded Bow-Tie Antenna

Low-profile directional ultra-wideband (UWB) antennas are strongly demanded in many UWB applications. However, few such UWB antennas have been reported. To meet the demands, an original novel low-profile directional UWB antenna-the self-grounded Bow-Tie is developed and presented here. This new UWB antenna has a compact and simple geometry, and ultra-wideband performance, such as presented here over a frequency range of 2-15 GHz with about -10 dB reflection coefficient, stable radiation patterns, and good time-domain impulse response. Measurements of a prototype of the antenna have verified the design and the simulation. It can be foreseen that this new antenna will find many applications in the different areas in UWB technology.

LOW-PROFILE DIRECTIONAL ULTRA-WIDEBAND ANTENNA FOR SEE-THROUGH-WALL IMAGING APPLICATIONS

A compact-size planar antenna with ultra-wideband (UWB) bandwidth and directional patterns is presented. The antenna can be fabricated on a printed circuit board (PCB). On one side of the PCB, it has a circular patch, and on the other side it has a slot-embedded ground plane with a fork-shaped feeding stub in the slot. Directional radiation is achieved by using a reflector below the antenna. To reduce the thickness of the antenna, a new low-profile antenna configuration is proposed. Three types of directional UWB antennas are analyzed. The distance between the antenna and the reflector is 12 mm (0.16 λ0, λ0 is the free space wavelength at the lowest frequency). In order to validate the design, a prototype is also fabricated and measured. Measured results agree well with the simulated ones. The measured results confirm that the proposed antenna features a reflection coefficient below -10 dB over the UWB range from 4.2 GHz to 8.5 GHz, a maximum gain around 9 dBi, a front-to-back ratio over 17 dB and pulse fidelity higher than 90% in the time domain. Thus it is promising for see-through-wall imaging applications.

A Planar, Differential, and Directive Ultrawideband Antenna

A novel planar differential ultrawideband antenna is described and both numerically and experimentally characterized. The proposed antenna is formed by two disc monopoles fed by 50-Ohm microstrip lines with a structured ground plane. Simulations and measurements demonstrate that it is possible to achieve a huge increase in directionality with respect to conventional monopoles by carefully engineering the ground plane and by exploiting the array effect.

Novel ultra‐wideband bow‐tie antenna with high front‐to‐back ratio and directivity

AbstractWe present a novel directional ultra‐wideband antenna based on the bow‐tie geometry. The proposed design, unlike the conventional bow‐tie radiator, has an inherently different radiation mechanism, which relies on magnetic currents excited in properly designed slots. This in turn allows to maintain good antenna performance even when a planar reflector is placed below the antenna that gives rise to high front‐to‐back ratio and directivity over a band extending from 4.8 to 6.1 GHz. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1016–1020, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25108

Analysis, Design and Realization of a Novel Directive Ultrawideband Antenna

In this paper, we present a simple log-periodic-dipole-array (LPDA) solution that allows us to achieve good ultrawideband (UWB) performances. The antenna has been manufactured and the measurements agree well with the theoretical predictions. The antenna presents an average gain of 8 dB and a return loss better than -10 dB over the band from 4.2 to 10.6 GHz. Both the measured antenna transfer function and the computed effect on pulse transmission show good performances in comparison with already known UWB antennas.

Directive Antenna for Ultrawideband Medical Imaging Systems

A compact and directive ultrawideband antenna is presented in this paper. The antenna is in the form of an antipodal tapered slot with resistive layers to improve its directivity and to reduce its backward radiation. The antenna operates over the frequency band from 3.1 GHz to more than 10.6 GHz. It features a directive radiation with a peak gain which is between 4 dBi and 11 dBi in the specified band. The time domain performance of the antenna shows negligible distortion. This makes it suitable for the imaging systems which require a very short pulse for transmission/reception. The effect of the multilayer human body on the performance of the antenna is also studied. The breast model is used for this purpose. It is shown that the antenna has more than 90% fidelity factor when it works in free space, whereas the fidelity factor decreases as the signal propagates inside the human body. However, even inside the human body, the fidelity factor is still larger than 70% revealing the possibility of using the proposed antenna in biomedical imaging systems.